These rear end caps fit standard Neo and Neo Ultimate hubs running 12x135mm or 12x150mm thru-axle spacing. If your Stan's hubs came spec'd for a different axle standard and you're moving the wheelset to a new frame, swapping end caps adapts the hub without replacing the entire wheel. The SealLock design uses a low-friction U-cup seal that snaps into position and stays put even when the wheel comes off the bike, keeping moisture and trail debris out of the bearing assembly.

Compatibility matters here. These caps work with standard Neo and Neo Ultimate rear hubs only. They won't fit the OS (oversized) hub variants, Center Lock rotor hubs, or the newer E-Sync and M-Pulse platforms. If you're running a Specialized frame with SCS dropouts at 12x135mm spacing, you'll need to install the non-SCS hub dropout kit before these end caps will work correctly. The machined alloy construction handles the loads rear hubs see under hard pedaling and drivetrain torque, and each cap carries stamped identification markings for sorting through parts bins when you've accumulated multiple axle configurations. Kit includes one pair of end caps with no axle hardware included.